File content as of revision 0:89cc1300ce7e:

#include "mbed.h"
#include <map>
#include <string>

//Initialize serial comms
Serial pc(USBTX, USBRX);

PwmOut PWMh(p26);
PwmOut PWMl(p21);

DigitalOut row1(p25);
DigitalOut row2(p22);
DigitalOut row3(p23);
DigitalOut row4(p24);

DigitalIn col1(p20);
DigitalIn col2(p19);
DigitalIn col3(p18);
DigitalIn col4(p17);
Timer t1;

//map
map<int, char> keypadMap;
map<int, char *> dtmfMap; 

//Mores Code -> Character Map
void init(){
        keypadMap[0x11]='1';
        keypadMap[0x12]='2';
        keypadMap[0x14]='3';
        keypadMap[0x18]='A';
        keypadMap[0x21]='4';
        keypadMap[0x22]='5';
        keypadMap[0x24]='6';
        keypadMap[0x28]='B';
        keypadMap[0x41]='7';
        keypadMap[0x42]='8';
        keypadMap[0x44]='9';
        keypadMap[0x48]='C';
        keypadMap[0x81]='*';
        keypadMap[0x82]='0';
        keypadMap[0x84]='#';
        keypadMap[0x88]='D';
        
        dtmfMap[0x11]="1029,697"; //1
        dtmfMap[0x12]="1336,697"; //2
        dtmfMap[0x14]="1477,697"; //3
        dtmfMap[0x18]="1633,697"; //A
        dtmfMap[0x21]="1209,770"; //4
        dtmfMap[0x22]="1336,770"; //5
        dtmfMap[0x24]="1477,770"; //6
        dtmfMap[0x28]="1633,770"; //B
        dtmfMap[0x41]="1209,852"; //7
        dtmfMap[0x42]="1336,852"; //8
        dtmfMap[0x44]="1477,852"; //9
        dtmfMap[0x48]="1633,852"; //C
        dtmfMap[0x81]="1209,941"; //*
        dtmfMap[0x82]="1336,941"; //0
        dtmfMap[0x84]="1477,941"; //#
        dtmfMap[0x88]="1633,941"; //D
}

int main() {
    init();
    //Initialize rows to 0
    row1 = 0;
    row2 = 0;
    row3 = 0;
    row4 = 0;
    t1.start();
    int cur_input = 0x00;
    int prev_input = 0x00;
    while(1) {
        //make all rows 0 to add stability
        row1 = 0;
        row2 = 0;
        row3 = 0;
        row4 = 0;
       //Keep each led lit for 4ms
       switch(t1.read_ms()%4){
                        case 0:
                        row1 = 1;
                        cur_input |= 0x10;   
                        break;
                        case 1:
                        row2 = 1;
                        cur_input |= 0x20;
                        break;
                        case 2:
                        row3 = 1;
                        cur_input |= 0x40;
                        break;
                        case 3:
                        row4 = 1; 
                        cur_input |= 0x80;
                        break; 
                        }
     if(col1 == 1)
     cur_input |= 0x01;
     else if(col2 == 1)
     cur_input |= 0x02;
     else if(col3 == 1)
     cur_input |= 0x04;
     else if(col4 == 1)
     cur_input |= 0x08;
     else cur_input = 0;
     
     
     if(cur_input) {
        if(cur_input != prev_input) {
            char c = keypadMap[cur_input]; //assign charcter based on input
            if(c != 0){
                pc.printf("%c\r",c);  //print input and char
            }
            float freqh,freql;
            char *freq = dtmfMap[cur_input];
            sscanf(freq,"%f,%f",&freqh,&freql);
            pc.printf("High:%f, Low:%f\r",freqh,freql);
            PWMh.period(1/freqh);               // set PWM period to user specified   
            PWMh=0.5;                         // set duty cycle to 50% 
            PWMl.period(1/freql);               // set PWM period to user specified   
            PWMl=0.5;                         // set duty cycle to 50%
            prev_input = cur_input;
        }
         
    }
    else {
        PWMh = 0.0;
        PWMl = 0.0;
     } 
    }
}